I'm not sure if it's an iguana I remember seeing another similar lizard at a reptile park that was about the same size and colour and it was arborial. But considering this was at an aquarium, it probably is marine iguana
@RezonantVoid. No idea what it was. They did have an enclosure within the aquarium that looked arboreal, but iguanas in there were much smaller, and had no way of getting out, plus no water other than to drink. This one was out and about like it owned the place, and it could go into the Carribean Sea or Atlantic Ocean (not sure which of the 2) if it wanted to. This was at an aquarium in the Dominican Republic.